But a visit by NASA astronaut Greg Chamitoff to Mount Annan Botanic Garden this week has raised hopes that science fiction could become reality.

Dr Chamitoff shared the results of a 12-month ``Seeds in Space'' study conducted by the Botanic Gardens Trust with the help of NASA.

More than 2500 waratah, flannel flower, golden wattle and wollemi pine seeds called the International Space Station home for six months as part of the cosmic experiment to see if the time in space, the lack of gravity and higher radiation levels affected the seeds' ability to germinate and grow when back on Earth.

The tests so far show that the time in space has had no effect on the viability of the seeds.

``This is a very important way to protect species and how better to do that than to store the seeds actually off the planet,'' Dr Chamitoff said.

``There is a complementary interest that NASA has in storing seeds in space.

``We'd like to be able to explore further and deeper in space and to live and work in space and on other planets.

``The key to being able to do that is going to depend a lot on being able to grow plants in space.''

The seeds were launched on Space Shuttle Discovery on May 31, 2008 and over the following six months they were exposed to the cosmic and solar radiation astronauts face when in space about 100 times the amount experienced on Earth.

It took another six months to get the seeds through quarantine and back to Mount Annan for testing.

So what is the significance of such an experiment?

``These are very encouraging results,'' Dr Chamitoff said.

``It means the possibility of long-term seedbanking in space is maybe an approach to protecting plant species on Earth.

``And it means these Australian seeds and other seeds are potentially capable of being transported in space to germinate and come one day be thriving in human colonies in space and on other planets.''

It appears the universe is now the limit when it comes to continuing the preservation work of Mount Annan Botanic Garden's famed seedbank.

Royal Botanic Gardens Trust executive director Tim Entwisle said: ``The safest place on Earth may well be off Earth.''